Process and system for the recovery of viscous oil



June 4, 1968 w. J. BIELSTEIN ETAL 3,386,508

PROCESS AND SYSTEM FOR THE RECOVERY OF VISCOUS OIL Filed Feb. 21, 1966 2Sheets-Sheet 1 SHALE SLOTTED CASING I I INVENT0R$ l m rum .LBIELSTEII, lBY mum mun,

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June 4, 1968 PROCESS AND SYSTEM FOR THE RECOVERY OF VISCOUS OIL FiledFeb. 21, 1966 W. J. BIELSTEIN ETAL INJECTION FLUlD $TE/AM & nor WATER-now SLOTTED sscnou 21 STEAM & HOT WATER FLOW 2 Sheets-Sheet 2IIIIIIIIIIIIIIIIIHHI:

- INVENTORS,

.BIELSTEII, GJIHL,

United States Patent 3,386,508 PROCESS AND SYSTEM FOR THE RECOVERY OFVISCOUS OIL Walter J. Bielstein and Lawrence G. Raw], Houston, Tex.,assignors to Esso Production Research Company Filed Feb. 21, 1966, Ser.No. 529,020 10 Claims. (Cl. 166-11) ABSTRACT OF THE DISCLOSURE A wellbore is drilled into a subsurface formation containing viscous oil andthen a plurality of wells is drilled to intersect the well bore and hotfluid is injected into the formation through the plurality of wells tocause viscous hydrocarbons to flow into the well bore.

The present invention is directed to recovery of viscous oil. Moreparticularly, the invention is concerned with the recovery of viscousoils by the use of heat. In its more specific aspects, the invention isconcerned with the recovery of viscous oils in which heated fluids areinjected into a subsurface earth formation containing the viscous oils.

The present invention may be briefly described as a method of recoveringviscous hydrocarbons from a subsu-rfiace earth formation containing theviscous hydrocarbons in which a well bore is drilled at least into thesubsurface earth formation containing the viscous hydrocarbons. Thiswell bore may be relatively large and may have a diameter ranging fromabout 1 to about 10 feet. Preferably, it will have a diameter in therange from about 2 to about 5 feet. The well bore may be drilled toprovide a sump in which the viscous oil may accumulate. A plurality ofwells is then drilled to intersect the well bore in the subsurfaceformation at a point preferably above the bottom of the well .bore. Thewell bore and the plurality of wells communicate fluidly with thesubsurface formation. A heated fluid which may be air, steam, hot water,combustion products or the like may be injected into the formation fromthe plurality of wells. Injection of the heated fluid causes heating ofthe subsurface formation and, therefore, causes the viscosity of theviscous hydrocarbons to be reduced to the extent that the viscoushydrocarbons flow into and accumulate in the well bore. The heatedviscous hydrocarbons may flow through the formation to the well boreand/or into the plurality of wells and thence into the well bore.Ordinarily, both flows may occur. Thereafter, the viscous hydrocarbonsmay be removed from the well bore such as by pumping.

The temperature of the heated fluid, whether it be steam, hot water, airor combustion products, should be sufficient to heat the formation andto cause the viscous hydrocarbons to flow. A suitable temperature of theheated fluids may range from about 150 F. to about 650 F.

In the practice of the present invention, it is contemplated that thewell bore Will be of relatively large diameter such as a diameter in therange of about 1 to about feet. A well bore ranging in diameter fromabout 2 to about 5 feet may be satisfactory. Likewise, in accordancewith the present invention, the well bore should be drilled into theformation a suflicient distance "ice to provide a sump in which theviscous hydrocarbons accumulate. Thus, the well bore may be drilledcompletely through the subsurface formation containing the viscoushydrocarbons to provide a sump for the viscous hydrocarbons. The wellbore may or may not be cased or lined with pipe.

Conversely, the wells Which intersect the Well bore should intersect thewell bore at a point above the bottom of the well bore such that a Sumpis provided for accumulation of viscous hydrocarbons in the well bore.

In accordance with the present invention, it is contemplated that theheated fluid will be injected selectively from the plurality of wellsinto the subsurface formation to cause heating of same and reduction ofviscosity of the viscous hydrocarbons. Preferably, the heated fluid isinjected selectively near the top of the viscous hydrocarbon-containingsubsurface earth formation, but it is within the contemplation of thepresent invention that the heated fluid may be injected at any selectedpoint in the subsurface formation. This may be accomplished by providinga vertically movable valved injector pipe or tubing in each of theWells. The pipe is valved at its lower end and is also provided with apacker means just above the valve. A section of the pipe is slotted orperforated above the packer to allow fluid communication between theinterior and exterior of the pipe. The valve means may be opened byresponse to certain temperatures or pressures. As the pipe is moveddownwardly in the Well, the packer and closed valve control the area offluid injection into the formation.

Another means of injecting the heated fluid at a selected point is toprovide a valved pipe similar to that mentioned above with the addedprovision of two packers spaced apart, above and below the perforated orslotted section. In either case, all or part of the heated fluids may bepumped into the formation or through the well bore to the recovery well.

The present invention also involves a system for recovery of viscoushydrocarbons from a subsurface earth formation containing the viscoushydrocarbons which involves a well bore penetrating the subsurfaceformation having openings or perforations into the subsurface formation.A plurality of wells intersect the well bore in the subsurface formationand extend laterally through the subsurface formation, each of theplurality of wells having openings or perforations into the subsurfaceformation. Means are provided in each of the plurality of wells forinjecting a heated fluid from the wells at least at a selected pointinto the subsurface earth formation. Means are provided in the Well borefor recovering viscous hydro-carbons which flow into and accumulate inthe well bore. Such means may include a pumping or other lifting means.The present invention is quite advantageous and useful in that it allowssubstantially complete recovery of viscous hydrocarbons from subsurfaceearth formations which heretofore has been accomplished only withdifficulty.

The present invention will be further illustrated by reference to thedrawing in which:

FIGURE 1 is a sectional view of a system in which the present inventionmay be employed;

FIGURE 2 is a top view looking down on an arrangement of wells inaccordane with the present invention;

FIGURE 3 is an enlarged fragmentary view of a por- 3 'tion of FIGURE 1illustrating fluid action or flow during operation of the presentinvention; and

FIGURE 4 is a view partly in section illustrating a modification of thedevice of FIGURE 3.

Referring now to the drawing and particularly to FIG- URES 1 and 2,numeral 11 designates the earths surface from which a well bore 12 hasbeen drilled by well known means to penetrate a subsurface earthformation 13 and to extend therethrough into an impervious formation 14.Also drilled into the subsurface earth formation 13 which containsviscous oil is a plurality of wells 15, 16, 17 and 18 which are drilledthrough the formation 13 and intersect the well bore 12. Extending fromthe earths surface into the well bore 12 is a tubing string 19 carryinga pump means 20 or other oil lifting means which is arranged adjacentthe bottom of the well bore 12. Each of the wells 15, 16, 17 and 18 isprovided, respectively, with casings 21, 22, 23 and 24.

The section of the well bore 12 below the casing 25 is suitably aslotted liner 26. Similarly, the sections of the casings 21, 22, 23 and24 in the subsurface earth formation 13 may be slotted liners 27, 28, 29and 30. Such slotted liners are well known.

The arrangement of the well bore 12 and the wells such as and 16 isshown in FIGURE 2 as a top view. Although only four injection wells areshown in FIGURE 1, it will be evident from FIGURE 2 that any desirednumber of wells may be drilled about the recovery well 12 to adequatelyblanket the desired area of recovery.

Each of the well casings 21-24 have positioned therein an injector pipeor tubing 31 which is movable vertically within the casing such as 21,illustrated in FIGURE 3. Tubing 31 has valve means 32 positioned at itslower end and also a packer means 33 just above the valve means. Thesection of tubing just above the packer 33 is provided with slots orperforations 34. The upper end of tubing 31 passes through a pack-offwellhead 35 (see FIGURE 1) and is valved at its upper end and alsoconnected to a source of heated fluid. The wellhead 35 is also providedwith a valved conduit 36 which is also connected to the source of fluid.The conduit 36 fluidly connects with the annulus between the casing andtubing. The valves are operably responsive (for opening and closing) tospecific temperatures or pressures.

Referring now to FIGURE 4, it will be seen that the tubing such as 31Ahas been modified to provide two packer means such as 33 and 33A whichare positioned, respectively, below and above the perforations 34 toafford a straddle pack effect. The tubing 31A is also provided with thevalve means 32 at its lower end below packer means 33.

The present invention operates as follows. It will be assumed that thewells 12-18 have been drilled as in dicated and the tubing strings 19and located as shown. A heated fluid such as air, steam or hot water, orflue gases at a temperature in the range indicated is then introducedinto the formation surrounding the slotted sections of the wells 15, 16,17 and 18. The tubing during this injection operation may be moved upand down in the casing with the valve 32 open or closed depending on theoperation. Fluid such as steam may be introduced through the tubing andtubing-casing annulus A for the purpose of maintaining the heat in theformation adjacent the perforated liner. Until a large amount of heathas been dissipated into the formation, steam will need to be cycledthrough the injected well bores.

As the formation surrounding the slotted section, such as 27 shown inFIGURE 3, is heated, the viscosity of the oil is reduced to a point suchthat it flows into the well bore below the packer 33 and, hence, intothe recovery well 12 and forms a body of oil 40 which may be then liftedto the surface by means of the pump 20 and tubing string 19. Althoughmuch of the lowered viscosity oil fiows through the various drain Wellsto the recovery well, it

is evident that part of the oil may flow directly from the formationinto the sump of the recovery well 12.

As the formation surrounding the slotted section, such tion is indicatedby the short, arrowed lines while steam and hot water flow is indicatedby the long curved arrowed lines. The flow of oil and water into therecovery well 12 is indicated by the heavy arrowed lines.

While it may be preferred to introduce the hot or heated fluid into theformation 13 adjacent the top thereof as shown in FIGURE 3, it is withinthe contemplation of the present invention to introduce the hot fluidselectively into any portion of the formation 13. Thus, at the beginningof the operation, it may be desirable to introduce the hot fluid nearthe top of the formation 13 and thereafter selectively and/orprogressively introduce the hot fluid at lower points in the formation.This may be accomplished also by moving a tubing string such as 31carrying a valve, such as 32, and packer 33 down any of the wells 15,16, 17 or 18 and causing same to open by pressure differential, specifictemperature, or by manipulation by wire lines from the surface as may bedesired. For specific spotting of injection fluids into the formation,it is evident that the straddle packers of FIG- URE 4 would be moredesirable.

The techniques for drilling large shafts ranging in diameter from 1 to10 feet are well known and, therefore, will not be described furtherherein. Likewise, the techniques for drilling directional wells are wellknown and need not be described further.

As examples of types of viscous oil which may be recovered in accordancewith the present invention, there are oil fields in California, Kansasand Texas, and elsewhere in the world which are susceptible to treatmentin accordance with the present invention and recovery of hydrocarbonstherefrom. Thus, the present invention is quite important and useful andalso advantageous.

Ths nature and objects of the present invention having been completelydescribed and illustrated, and the best mode and embodiment contemplatedset forth, what we wish to claim as new and useful and secure by LettersPatent is:

1. A method of recovering viscous oil from a subsurface formationcontaining said viscous oil which comprises:

drilling a well bore at least into said subsurfaces formation;

drilling a plurality of wells to intersect said well bore in saidsubsurface formation;

said well bore and said plurality of wells communicating fluidly withsaid subsurface formation; injecting a heated fluid into said formationfrom said plurality of wells;

thereby causing said viscous oil to flow into and accumulate in saidwell bore; and

recovering said viscous oil from said well bore.

2. A method in accordance with claim 1 in which the heated fluid issteam.

3. A method in accordance with claim 1 .in which the heated fluid is hotwater at a temperature sufiiciently above formation temperature to causesaid viscous oil to flow.

4. A method in accordance with claim 1 in which the heated fluid is agas.

5. A method in accordance with claim 1 in which the well bore is of adiameter substantially greater than the diameter of each of saidplurality of wells and said well bore extends below the point where saidWells intersect the well bore.

6. A method in accordance with claim 1 in which heated fluid is injectedselectively from said plurality of wells at a point adjacent the top ofsaid subsurface formation.

7. A method in accordance with claim 1 in which said viscous oil isrecovered from said well bore by pumping.

8. A method in accordance with claim 1 in which the plurality of wellsis directionally drilled from horizontally spaced-apart points on theearths surface from said well 5 bore through said subsurface formationto expose a large area of each of said plurality of wells to saidsubsurface formation.

9. A method in accordance with claim 1 in which the heated fluid isinjected into said subsurface formation from selected points in saidplurality of wells.

10. A system for recovery of viscous oil from a subsurface earthformation containing viscous oil which comprises:

a well bore penetrating said subsurface formation having openings intosaid subsurface formation;

a plurality of wells intersecting said well bore in said subsurfaceformation extending laterally through and having openings into saidsubsurface formation;

means in said wells for injecting a heated fluid from said wells atleast at a selected point into said subsurface formation; and

means adjacent the bottom of said well bore for recovering viscous oilwhich flow into and accumulate in said well bore.

References Cited UNITED STATES PATENTS Pevere et a1 166-11 Hennig 166-11Tek et al 166-11 Woodruff 16611 X Rogers et al. 166-11 Cryer 16652Hamilton et al 16611 X Thompson et al. 166-41 Dougan 16611 STEPHEN I.NOVOSAD, Primary Examiner.

